Silk from the silkworm Bombyx mori is a versatile biomaterial that has been valued for its use in the medical, research, cosmetic, and textile industries. Raw silk from the silkworm is composed primarily of two high-molecular weight proteins. The actual silk fibers are composed of fibroin polypeptides, and the “glue” that cements the fibers together is composed of sericin polypeptides. Depending on the intended utility of the raw silk, the fibroin and sericin components of silk must be separated from one another in a process known as “degumming” to obtain fibroin preparations that are substantially free of sericin and sericin preparations that are substantially free of fibroin. Silk fibroin preparations that are substantially free of sericin are preferred, for example, if the silk is desired for medical applications because the presence of sericin has been shown to produce unwanted thrombogenic and/or inflammatory responses. On the other hand, silk sericin preparations that are substantially free of fibroin are preferred, for example, if the silk is desired for certain cosmetic uses, such as for incorporation into shampoo as an additive, which has been shown to coat hair and provide a protective transparent film that improves hair luster and flexibility.
Despite the widespread utility of silk, there remains an unmet need to develop sensitive and accurate diagnostic compositions and methods for evaluating sericin content of silk materials.